PEF technology has found a wide range of applications in different areas such as, for example, bio-fouling control, non-thermal food processing, odor control, and NOx removal. Extensive research has been conducted to study the efficacy of using PEF as a non-thermal food pasteurization/sterilization method. However, the application of PEF treatment is not straightforward due to a number of factors. Factors affecting PEF treatment include, for example, electric field strength, treatment temperature, stage of microbial growth, and total treatment time.
In typical PEF treatment systems, high voltage pulses are induced in food products by specially designed PEF treatment chambers. Fluid food products are primarily conductive due to the existence of charge carrying particles such as, for example, proteins, vitamins and minerals. Therefore, application of a high-voltage across a treatment chamber results in a large flux of current flowing through the food product. This same current must also flow through the high-voltage pulse generator that is generating the high-voltage pulse(s).
In this regard, a PEF treatment chamber generally has two electrodes that convert high-voltage pulses to pulsed electric fields. Food product residing in between the electrodes is exposed to this field. For effective treatment, the design of the treatment chamber should guarantee a uniform field distribution inside the treatment zone. However, due to the large contact area between the two electrodes, the resistance therebetween is typically small and often in the range of half an Ohm to a couple of Ohms. Consequently, it is difficult for conventional high-voltage pulse generators to drive a PEF treatment chamber that has such a small resistance.
Accordingly, conventional high-voltage pulse generators are disadvantageous for a number of reasons. One disadvantage is that few high-voltage pulse generators can maintain the extremely high currents required due to the low resistances of treatment chambers. Additionally, conventional high-voltage pulse generators only provide for unipolar pulses that cause the deposition of protein and other charge carrying particles on electrodes. Therefore, methods and apparatuses for providing high-voltage pulses that do not suffer from these and other disadvantages are desirable.